Strong resonant coupling for short-range wireless power transfer applications using defected ground structures

This paper presents a new structure for highly efficient short-range wireless power transfer. The proposed structure is based on strongly coupled resonators using H-slot defected ground structures. An equivalent circuit model for H-slot coupled resonators is introduced. Measurement results for the new proposed structure show a power transfer efficiency of 70% at 15 mm distance between driver and load resonators. Experimental measurements have shown good agreement with electromagnetic and circuit simulations.

I. Introduction

The growing demand of wireless power transfer (WPT) technology, especially non-radiative techniques, is interesting for its wide potential applications like RFIDs, implanted medical devices, electric vehicles, and portable electronic devices [1]–[3]. Non-radiative or near field techniques are based on inductive or capacitive coupling for short-range applications, and resonant inductive coupling for mid-range applications. Inductive coupling is the most popular technique for high power transfer, and is usually applied at the lower frequency region [4]. At higher frequencies, the resonant type becomes a good choice. Resonant circuits focus the power at a certain frequency, so that power transfer efficiency can be improved [5]. On the other hand, strong resonant coupling uses intermediate resonators with high Q-factors to increase the total efficiency of transferred power [6].